Nozzle movement system for laser machining equipment

ABSTRACT

Disclosed is a nozzle movement system for a laser machining equipment for moving the nozzle of a CNC laser machining equipment when carrying out a three-dimensional machining of a machining surface of a workpiece. A hand coordinate system composed of the axial direction of the nozzle and the plane perpendicular to the axis of the nozzle is provided, and a movement command on the hand coordinate system is output by using a machine operation panel (31). A matrix creation means (38) creates a conversion matrix from the hand coordinate system to a basic coordinate system, based on the rotational position data stored in registers (39a, 39b) of an α-axis and β-axis exhibiting the attitude of the nozzle. A coordinate conversion means (37) converts movement commands (Δxh, Δyh and Δzh) on the hand coordinate system to amounts of movement (Δx, Δy and Δz) on the basic coordinate system, by using the conversion matrix, and moves the nozzle. With this arrangement, the nozzle can be simply moved without changing the distance between the nozzle and the machining surface of a workpiece. Further, the distance between the nozzle and the workpiece can be adjusted by moving the nozzle perpendicularly with respect to the machining surface.

DESCRIPTION

1. Technical Field

The present invention relates to a nozzle movement system for a lasermachining equipment, by which the nozzle of a CNC laser machiningequipment for carrying out a three-dimensional machining is moved withrespect to a machining surface, and more specifically, to a nozzlemovement surface for a laser machining equipment by which a nozzle canbe easily moved along the plane surface of a workpiece.

2. Background Art

A NCN laser machining equipment composed of a combination of a laseroscillator and a numerical control apparatus (CNC) is widely used. Inparticular, a machining of a complex configuration can be carried out ata high speed by a non-contact system, due to a combination of thecharacteristics of the laser machining equipment by which a machiningcan be carried out at a high speed and the characteristics of thenumerical control apparatus (CNC) by which a complex contour can becontrolled. Particularly, a CNC laser machining equipment capable ofcarrying out a three-dimensional machining which cannot be carried outby a conventional punch press, nibbling machine and the like is put topractical use.

To carry out a three-dimensional machining by the CNC laser machiningequipment, the attitude of the nozzle at an extreme end must becontrolled, in addition to a control of X-, Y- and Z-axes, and thecontrol axes used for this purpose are referred to as an α-axis andβ-axis. The attitude of the nozzle is controlled by a zero offset typecontrol or an offset type control.

In this three-dimensional laser machining equipment, a machining programis created by moving a nozzle on the surfaces of an actual workpiece andteaching machining points. At this time, the attitude of the nozzle iscontrolled so that the nozzle is perpendicular to a machining surface ofthe workpiece, and a predetermined distance is maintained between thenozzle and the machining surface. This is carried out to ensure that alaser beam is focused on a given position on the plane surface of theworkpiece.

To achieve the above object, when the machining points are taught, thenozzle must be moved in the same direction as that in which the surfaceof the workpiece is machined, while maintaining the predetermineddistance between the machining surface and the nozzle. Further, when thedistance between the nozzle and the workpiece is adjusted, the nozzlemust be moved perpendicularly with respect to the machining surface.

Nevertheless, if the plane surface of the workpiece to be subjected to athree-dimensional machining is not parallel to the X-Y plane, theattitude of the nozzle does not coincide with the axis of a basiccoordinate, i.e., the nozzle is inclined. Therefore, it is verydifficult to control the movement of the nozzle by using a usualoperation panel by which movements in the X-, Y- and Z-axis directionsare carried out in a basic coordinate system while maintaining apredetermined distance between the nozzle and the machining surface ofthe workpiece. Further, it is very difficult to adjust the distancebetween the nozzle and the machining surface by using the usualoperation panel.

DISCLOSURE OF THE INVENTION

Taking the above into consideration, an object of the present inventionis to provide a nozzle movement system for a laser machining equipment,by which a nozzle can be moved while maintaining a predetermineddistance between the nozzle and the machining surface of a workpiece.

To attain the above object, according to the present invention, there isprovided a nozzle movement system for a laser machining equipment, formoving the nozzle of a CNC laser machining equipment when carrying out athree-dimensional machining of a machining surface, the systemcomprising a movement-command means for outputting a movement command ona hand coordinate system composed of the axial direction of the nozzleand the plane perpendicular to the nozzle, by manually feeding thenozzle on the hand coordinate system, a matrix creation means forcreating a matrix for converting the movement command to an amount ofmovement on a basic coordinate system based on the rotational positiondata of an α-axis and β-axis for controlling the attitude of the nozzle,and a coordinate conversion means for converting the movement command tothe amount of movement by using the matrix.

The movement command means provides the hand coordinate system composedof the axial direction of the nozzle and the plane perpendicular to theaxis of the nozzle, and outputs the movement command on the handcoordinate system. The movement command means can be arranged as amachine control panel. The matrix creation means creates the conversionmatrix from the hand coordinate system to the basic coordinate system,based on the rotational position data of the α-axis and β-axisexhibiting the attitude of the nozzle. The coordinate conversion meansconverts movement commands on the hand coordinate system to amounts ofmovement on the basic coordinate system by using the conversion matrix,and moves the nozzle. With this arrangement, the nozzle can be easilymoved without changing the distance between the nozzle and the machiningsurface of a workpiece, and further, the distance between the nozzle andthe workpiece can be adjusted by moving the nozzle perpendicularly withrespect to the machining surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a process for converting a movement commandon a hand coordinate system to an amount of movement on a basiccoordinate system;

FIG. 2 is a diagram showing the relationship between a workpiece and anozzle;

FIG. 3 is a block diagram of the hardware of a numerical controlapparatus (CNC), for controlling a three-dimensional laser machiningequipment;

FIG. 4 is a partial diagram of an arrangement of an offset type nozzlehead mechanism; and

FIG. 5 is a diagram explaining a method of determining a conversionmatrix for converting a hand coordinate system to a basic coordinatesystem.

BEST MODE OF CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below withreference to the drawings.

FIG. 2 shows the relationship between a workpiece and a nozzle. Themachining surface 102a of a workpiece 12 is inclined with respect to theX-Y plane 101 of a basic coordinate system, and therefore, the attitudeof the nozzle 103 is controlled to be made perpendicular to themachining surface 102a.

Here, the coordinate system formed by the machining surface 102a and theaxis of the nozzle 103 is defined as a hand coordinate system and thecoordinate axes thereof are represented by Xh, Yh and Zh, and thecoordinate axes of the basic coordinate system are represented by X, Yand Z.

For example, when a machining is carried out along a locus 104 on themachining surface 102a, the nozzle 103 must be moved so that a distanceΔl between the nozzle 103 and the machining surface is maintained at apredetermined amount. This is carried out to ensure that the focus of alaser beam is at a desired depth from the machining surface 102a.Therefore, when the nozzle 103 can be moved on the hand coordinatesystem, the nozzle 103 need only be moved on the Xh-Yh plane of the handcoordinate system. Further, when the distance Δl between the nozzle 103and the machining surface 102a must be changed, the nozzle 103 need onlybe moved in the direction of the coordinate axis Zh. More specifically,according to the present invention, the movement of the nozzle 103 iscontrolled in such a manner that the nozzle 10 is moved on the handcoordinate system, and this movement is converted to the basiccoordinate system (X, Y, Z).

FIG. 3 is a block diagram of the hardware of a numerical controlapparatus (CNC) for controlling a three-dimensional laser machiningequipment, wherein 10 designates a numerical control apparatus. Aprocessor 11, which serves as a central component for controlling thenumerical control apparatus (CNC) 10 as a whole, reads a system programstored in a ROM 12 through a bus 21 and controls the numerical controlapparatus (CNC) 10 as a whole according to the system program. A RAM 13stores temporary calculation data, display data and the like; an SRAM isused as the RAM 13. A CMOS 14 stores laser machining conditions, amountsof pitch error correction, machining programs, parameters and the like.This data is maintained as is even after a power supply to the numericalcontrol apparatus (CNC) 10 is cut off, because the CMOS 14 is suppliedwith power from a battery and is a non-volatile memory.

An interface 15 is connected to a machine operation panel 13 thatoutputs teaching data as a moving command on the hand coordinate system.The operation of the machine operation panel 31, and the movementcommand, will be described later in detail.

A programmable machine controller (PMC) 16 is incorporated in the CNC10, and control a machine in accordance with a sequence program createdin a ladder form. More specifically, the programmable machine controller(PMC) 6 uses the sequence program to convert the command for anauxiliary gas and the like instructed by the machining program to asignal needed by the machine, and output same to the machining throughan I/O unit 17. This output signal actuates magnets and the like,hydraulic valves, pneumatic valves, electric actuators, and the like ofthe machine. Further, the programmable machine controller (PMC) 16receives signals from the limit switches and the machine operation panelof the machine, and supplies same to the processor 11 after a necessaryprocessing of same.

A graphic control circuit 18 converts digital data such as the presentposition of each axis, alarms, parameters, image data and the like toimage signals and outputs same. These image signals are supplied to thedisplay unit 26 of a CRT/MDI unit 25 and displayed thereat. An interface19 receives data from the keyboard 27 in the CRT/MDI unit 25 andsupplies same to the processor 11.

An interface 20 is connected to a manual pulse generator 32 and receivespulses therefrom.

Each of the axis control circuits 41 to 45 receives a movement commandfor each axis from the processor 11, and outputs a command for each axisto each of the servo amplifiers 51 to 55, whereupon each of the servoamplifiers 51 to 55 receives the movement command and drives each of theservo motors 61 to 65 for the respective axes. Here, the servo motors 61to 65 drive the X-axis, Y-axis, Z-axis, α-axis and β-axis. Each of theservo motors 61 to 65 contains a position detecting pulse coder, andposition signals from the pulse coder are fed back as a pulse train.Further, this pulse train can be subjected to an F/V (frequency/speed)conversion to create a speed signal. The feedback line and speedfeedback of these position signals are not shown in the Figure.

A laser oscillating unit 80 is connected to an interface 71, and a laseroscillation output, oscillation frequency, pulse duty and the like areoutput therethrough by the numerical control apparatus 10. The laseroscillating unit 80 outputs a laser beam in accordance with thesecommands, and the laser beam is introduced to the nozzle and thenfocused on the workpiece for machining same.

FIG. 4 is a partial arrangement diagram of an offset type nozzle headmechanism. An α-axis servo motor 1 drives the α-axis and a β-axis servomotor 2 drives the α-axis. The laser beam 3 is introduced to the extremeend of a nozzle by a not shown reflection mirror, and irradiated to theworkpiece.

The α-axis is a rotation axis rotating about the Z-axis, and therotation of the α-axis servo motor 1 causes a member 5 to be rotated ofthe α-axis servo motor 1 causes a member 5 to be rotated through gears4a and 4b to thus control the rotation of the nozzle. The rotation ofthe β-axis servo motor 2 causes an axis 7 to be rotated through gears 6aand 6b, and the rotation of the axis 7 causes an axis 9 to be rotatedand controlled through bevel gears 8a and 8b. Designated at 9a is thenozzle fixed to the axis 9.

FIG. 5 is a diagram explaining a method of determining a conversionmatrix for converting the hand coordinate system to the basic coordinatesystem, wherein the nozzle is rotated by α° on the X-Y plane and theβ-axis is assumed to be rotated by β° at tis position.

Here, when the unit vectors of the Xh-, Yh- and Zh-axes on the handcoordinate system are represented on the basic coordinate system,respectively, by

    u (u.sub.x, u.sub.y, u.sub.z)

    v (v.sub.x, v.sub.y, v.sub.z)

    w (w.sub.x, w.sub.y, w.sub.z),

the respective elements are represented by

    u.sub.x =cosα

    u.sub.y =sinα

    u.sub.z =0

    u.sub.y =sinα

    w.sub.x =sinβ*sinα

    w.sub.y =sinβ*cosα

    w.sub.z =cosβ

The unit vector v of the Yh-axis can be calculated as the outer productof the unit vector u and the unit vector w, and therefore, the followingexpression can be obtained.

    v.sub.x =w.sub.y *u.sub.z -w.sub.z *u.sub.y

    v.sub.y =w.sub.z *u.sub.x -w.sub.x *u.sub.z

    v.sub.z =w.sub.x *u.sub.y -w.sub.y *u.sub.x

As a result, a conversion matrix A can be represented by the followingexpression. ##EQU1## The conversion from the hand coordinate system tothe basic coordinate system can be represented by the followingexpression.

    [ΔXΔYΔZ].sup.T =A[ΔxhΔyhΔzh].sup.T

FIG. 1 is a block diagram of a process for converting a movement commandof the hand coordinate system to an amount movement of the basiccoordinate system. The machine operation panel 31 includes jog buttons32a, 32b, 33a, 34a and 34b for moving the nozzle in each coordinate axisdirection. When a switch 35 is set to the left (H), these buttons outputmoving commands for the hand coordinated system, and when the switch isset to the right (B) conversely, these buttons output moving commandsfor the basic coordinate system.

When the jog button 32a (+X) is operated, assuming that the changingswitch 35 is set to the left (H), a movement command Δxh can be outputby which the nozzle is moved in the Xh-axis direction on the machiningsurface, without changing the distance between the nozzle and themachining surface. Further, when the button 34a (+Z) is operated, amovement command Δzh can be output by which the nozzle is moved in theZh-axis direction perpendicular to the machining surface. Here, the jogbutton 32a and the like are operated for moving the nozzle to the nextmachining point. Next, when a switch 36 is depressed, movement commandsΔxh, Δyh, and Δzh on the hand coordinate axis are output by themicroprocessor contained in the machine operation panel 31.

Conversely, the rotation angles of the α-axis and β-axis are stored inregisters 39a and 39b and a matrix creation means 38 calculates anddetermines the above conversion matrix A from these rotation angles. Acoordinate conversion means 37 converts the movement commands Δxh, Δyhand Δzh from the machine operation panel 31 to the amounts of movementΔx, Δy, and Δz on the basic coordinate system, by using the matrix A,and outputs same to the axis control circuits 51, 52 and 53,respectively.

As described above, the above teaching operation can be simply carriedout without changing the distance between the nozzle and the machiningsurface in such a manner that movement commands are output on the handcoordinate system, and are converted to the amounts of movement on thebasic coordinate system by the conversion matrix. Further, the nozzlecan be moved in the direction perpendicular to the machining surface,and thus the distance between the nozzle and the machining surface canbe easily adjusted.

Although the movement command is output from the machine operation panelin the above description, the machine operation panel can output only anoperation signal for the jog button, whereas a movement command on thehand coordinate system is created and converted to an amount of movementon the basic coordinate system in the numerical control apparatus.

Further, the nozzle is described above as an offset type nozzle, butsimilar operation also can be carried out by a zero offset type nozzle.In this case, however, the a zero offset type conversion matrix must beprepared.

As described above, according to the present invention, since a movementcommand on the hand coordinate system is output from the machineoperation panel and converted to a movement command on the basiccoordinate system by the conversion matrix, the position of the nozzlecan be simply controlled without changing the distance between themachining surface and the nozzle. Further, the distance between thenozzle and the machining surface can be easily adjusted.

Consequently, the creation of a machining program is simplified and thetime necessary for creating the machining program is shortened.

I claim:
 1. A nozzle movement system for a laser machining equipment formoving the nozzle of a CNC laser machining equipment carrying out athree-dimensional machining of a machining surface, comprising:amovement command means for outputting a movement command on a handcoordinate system composed of the axial direction of said nozzle and theplane perpendicular to said nozzle by manually feeding said nozzle onsaid hand coordinate system; a matrix creation means for creating amatrix for converting said movement command to an amount of movement ona basic coordinate system based on the rotational position data of anα-axis and β-axis for controlling the attitude of said nozzle; and acoordinate conversion means for converting said movement command to saidamount of movement by using said matrix.
 2. A nozzle movement system fora laser machining equipment according to claim 1, wherein said movementcommand means is composed of a machine operation panel that outputs saidmovement command according to an operation command from operationswitches.
 3. A nozzle movement system for a laser machining equipmentaccording to claim 2, wherein said machine control panel includes achanging switch for switching between a movement command based on saidbasic coordinate system and a movement command on said hand coordinatesystem.
 4. A nozzle movement system for a laser machining equipmentaccording to claim 1, wherein said movement command means is composed ofa machining control panel that outputs only a movement operation signal.5. A nozzle movement system for a laser machining equipment according toclaim 1, wherein said nozzle is an offset type nozzle.